Mussels are found worldwide. / Some live in the sea. / Others inhabit freshwater streams and lakes. / When you try to move a mussel from a rock，/ you will discover what an incredibly firm grip it has / —a necessity if the mussel is to resist the sharp grab of a hungry seabird or the pounding waves of the sea. /

 

How does it manage to cling so tight? / When it chooses a place to set up home, / it pokes its tongue-shaped foot out of its shell / and presses it against a solid surface. / Special glands give off a fluid mixture of proteins / into a channel that runs the length of the foot. / This liquid quickly hardens into a fine, / elastic thread about an inch long. / Then a tiny pad-like structure at the end of this thread give off some natural glue-like substance, / the mussel lifts its foot, and anchor line number one is complete. / These strategically placed threads form a bundle, / which ties the mussel to its new home in much the same way / that ropes hold down a tent. / The whole procedure takes only three or four minutes. /